Process of making sulfurous-acid compound of alpha-isatin anilid.



FRGCESS OE IVIAKIRG SULFUPJOUS-ACID COMPOUND 03 ALPZ-IA-ISATIN ANILID.

N Drawing.

To all whom "it may concern:

Be it. known that we CARL STEZHAN and Anyone BAHTJEN, subjects of the Emperor of Germaiy. residing at Hamburg, in the Empire of Germany, have invented certain new and useful improvements in Frocesses of Making Sulfurous-Acid Compounus of Alpha-lsatin Anilid and Its l'lomologues, of which the following is a specification.

T his llTv'C-llti-JH relates to a process of producing compounds of alpha-isatin anilid and its h inologues with sulfurous acid.

Vi e have discovered by experiment that compounds of alpha-isatin anilid and its homologues containing tne sulfurous acid radical can be produced from an acid solution of alpha-isatin anilid. so that it is unnecessary to neat alize the sulfuric or other acid used for holding the alpha-isatin anilid in solution or suspension. This discovery is of particijllar interest and impor ance as on ganic compounds containing the sulfurous acid radical cannot ordinarily be formed in the presence of any other acid stronger than sulfurous acid. and in fact such organic compounds are ordinarily decomposed by any other acid stronger than sulfur-oils acid.

lye have found when one part of diphenyloxalainidinthioamid is treated with four parts of hot sulfuric acid preferably of 66" Be. there obtained a solution of alphaisatin anilid in sulfuric acid. The separation of the alpha-isatin anilid from this acid solution in the usual way necessarily requires enormous antities of an alkali. as for example, soda, and ice. all of ti o sulfuric acid employed must be neutralized and the liquid well cooled in order to obtain the precipitate of alpha-isatin anilid. Furthermore in this process the alpha-isatin anilid formed has a strong tendency to decompose so that the process not only costly but impracticable.

in the practice of our process we pour an acid holding alpha-isatin anilid or a salt thereof. in solution or suspension. into sulfurous acid or into a solution of reagents containing or capable of giving off sulfur-ans acidv The acid containing the alpha-isatin anilid in solution or suspension must be diluted so as not to interfere with the reaction above described. Tue degree of dilution of the acid may vary widely, satisfactory results being obtained where one part of acid is diluted with five parts of wrter. In fact a mere trace of the free acid in water is ordi- Specifioation of letters Patent.

Application filed July 13; 908.

Patented Get. i9, 190%.

Serial No. 448,361.

iarily suliicient. Only sufficient sulfurous acid or compounds containing or capable of giving off sulfurous acid are required to be inolecularly equivalent to the alpha-isatin anilid present.

Ve are able to obtain satisfactory results if either the sulfurous acid or compounds containing or adapted to give oti this acid or the acid containing the alpha-isatin anilid in solution or suspension is diluted. In either case the sulfurous acid compound of the alpha-isatin anilid is produced and separates in the form of a reddish granular precipitate. The alpha-isatin anilid may be separated from the sulfurous acid compound of alpha-isatin anilid by adding alkali. as sodium hydroxid in molecular proportions, no ice being required to control the reaction.

The following examples illustrate various ways in which our process can be satisfactorily practiced.

Example No. 1: To kilograms of diphenyloxalamidintlioamid or a homologue therefor add 100 kilograms of hot sulfuric acid. A solution of 22 kilograms of alohaisatin anilid or a homologue thereof in the sulfuric acid will be obtained. Pour this solution into 1000 liters of water containii'ig 7 kilograms of sulfurous acid gas dissolved therein. Almost immediately there will be formed a precipitate of a sulfurous acid compound of alpha-isatin anilid or a homologue thereof. The precipitate may be separated from the liquid by decantation or filtration and the remaining liquid will consist of dilute sulfuric acid the sulfurous acid employed having; combined with the alphaisatin anilid or its homologue.

Example No. 2: Proceed directed in rixample No. l but instead of using dilute sultuious acid substitute therefor 10.5 k1lo stated quantity of dilute sulfurous acid and the sult'urous compound of alpha-isatin anilid will be formed, hydrochloric acid being set free.

It is to be understood that instead of using alpha-isatin anilid or a compound of alphaisatin anilid, homologues or corresponding compounds of homolognes may be employed and that the compounds, homologues and compounds of homologues of alpha-isatin anilid are the equivalents of alpha-isatin anilid in the practice of our process as hereinbcfore set forth.

Having described our invention, we claim,

1. The process of producing a compound of alpha-isatin anilid which consists in miX- ing an acid containing alpha-isatin anilid with a reagent containing the sulfurous acid radical.

2. The process of producing a compound of alpha-isatin anilid which consists in mixing an acid solution of alpha-isatin anilid with a reagent containing the sulfurous acid radical.

3. The process of producing a compound of alpha-isatin anilid which consists in miX- ing an acid solution of salts containing alpha-isatin anilid with a reagent containing the sulfurous acid radical.

6. The process of producing a compound of alphaisatin anilid which consists in mixing an acid solution of salts containing alpha-isatin anilid with sulfurous acid.

In testimony whereof we afiiX our signatures in presence of tWo witnesses.

CARL STEPHAN. ARNOLD RAHTJ EN.

Witnesses:

ERNEST H. L. MUMMENHOFF, G'r'ro \V. HILLMRIOH. 

